Managing conflicts arising from fisheries enhancements based on non‐native fishes in southern Africa

Abstract

Southern Africa has a long history of non-native fish introductions for the enhancement of recreational and commercial fisheries, due to a perceived lack of suitable native species. This has resulted in some important inland fisheries being based on non-native fishes. Regionally, these introductions are predominantly not benign, and non-native fishes are considered one of the main threats to aquatic biodiversity because they affect native biota through predation, competition, habitat alteration, disease transfer and hybridization. To achieve national policy objectives of economic development, food security and poverty eradication, countries are increasingly looking towards inland fisheries as vehicles for development. As a result, conflicts have developed between economic and conservation objectives. In South Africa, as is the case for other invasive biota, the control and management of non-native fishes is included in the National Environmental Management: Biodiversity Act. Implementation measures include import and movement controls and, more recently, non-native fish eradication in conservation priority areas. Management actions are, however, complicated because many non-native fishes are important components in recreational and subsistence fisheries that contribute towards regional economies and food security. In other southern African countries, little attention has focussed on issues and management of non-native fishes, and this is cause for concern. This paper provides an overview of introductions, impacts and fisheries in southern Africa with emphasis on existing and evolving legislation, conflicts, implementation strategies and the sometimes innovative approaches that have been used to prioritize conservation areas and manage non-native fishes.

Invasion status of the common carp Cyprinus carpio in inland waters of Argentina

“…This situation is in agreement with reservoir development in the Iberian Peninsula, where the species was introduced more than five centuries ago but its expansion and establishment has increased in the last century because of an increase in the construction of dams that have facilitated its spread (Clavero & Villero, ). A similar scenario has been found in southern Africa where C. carpio is usually found in most impoundments (Ellender et al ., ) where they are often the dominant species (Ellender et al ., ). Dams and reservoirs in south‐east Australia have also been shown to favour C. carpio (Koehn, ), reinforcing the relevance of reservoirs as key habitats for the species.…”

Trophic overlap between fish and riparian spiders: potential impacts of an invasive fish on terrestrial consumers

“…The invasive fish present in our study area were rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta; Fig. 1), both popular sport fish with invasive populations around the world, including South Africa, where they were introduced in the late 19th century (Ellender et al 2014). Outside of their native range (i.e., North America and Asia/Europe), they often have adverse consequences for native fish, invertebrates, and ecosystem functioning (e.g., Ruzycki et al 2003;Townsend 2003).…”

The ghost of introduction past: Spatial and temporal variability in the genetic diversity of invasive smallmouth bass

“…Here, they were reared and bred before being released into multiple water bodies across the country to provide opportunities for angling (De Moor & Bruton, 1988). Most of the documented stockings (De Moor & Bruton, 1988) occurred prior to the cessation of government support to stocking programs in the early 1990s (Ellender, Woodford, Weyl, & Cowx, 2014). …”